1. Field of the Invention
The invention involves a continuous process for separation of particles of a given size range from a preparation containing solid particles having a wide size distribution range. By way of example, small, heavy particles from biological preparations, such as tissue homogenates, can be easily separated from the larger particles associated with the biological debris present. Particles on the order of 1-2 microns and the like, such as inclusion bodies and like, which may contain or constitute, valuable biological materials, can be easily recovered in a substantially concentrated form. Inorganic materials over a given size distribution can be similarly separated in concentrated form.
2. Background of the Prior Art
For some time, it has been recognized that it is frequently desirable to concentrate specific particles from a biological preparation, which particles may contain or be valuable biological materials. Thus, it is known that various pesticides and similar agricultural treatments, can be prepared from viruses and other biological agents obtained from the insects sought to be regulated, rather than from artificial, and potentially hazardous, chemicals. One example is the natural virus pesticide being used to control the devastation raked by the gypsy moth in the northeastern United States, exemplified by the virus-based pesticide useful in controlling that moth, prepared from the nuclearpolyhedrosis virus that infects that species. In general, these viruses and similar biological agents, can be obtained from, inclusion bodies and similar small organelles or biomaterials found in the cells of the organisms in question. As an alternative embodiment, in cells prepared as expression vehicles by recombinant engineering, many valuable biological agents, such as interferon and interluken-2, are contained primarily in similar inclusion bodies. The isolation of these inclusion bodies, from other solid biological debris, remains a preliminary step to the utilization of these valuable biological agents.
Additionally, many products require effective, efficient and economical methods for increasing the concentration of particles of a given size from a raw material source. One example is the collection of clays from slurries of mined materials.
Current separation technologies are not adequate to the task of separating large and small solid particles from a liquid preparation, such as a biological homogenate without excessive coat. In general, these processes are confined to a simple separation, centrifugation and drying. Generally, this is inadequate to achieve a useful separation. This is particularly because the large solids leaving the screen, e.g., cheesecloth, carry water wetting their surfaces. Smaller sized solids will be entrained with the water. Thus, subsequent collection of large solids, followed by centrifugation, will not result in separation of the small and large particles. In the alternative, if the small particle is the desired recovery object, a substantial amount of small particle recovery will be missed, due to the retainment of those small particles in the large particle separation discussed above. Alternative, all-dry processing, fails to exclude undesirable particles from the final preparation obtained.
Accordingly, it remains an object of the industry to provide a simple, straightforward and effective method for the separation of particles, based on size discrimination, from a liquid preparation. Particular emphasis is placed on the separation of small, heavy particles, such as inclusion bodies, from larger particles of similar weight found in a biological preparation.